An Experimental Demonstration Of Converting Organic Liquids And Their Aqueous Solutions In A Film Boiling Reactor

摘要

This thesis presents an experimental demonstration of a chemical reactor design based on film boiling using aqueous mixtures of ethylene glycol. Termed a Film Boiling Reactor (FIBOR), the reactor volume is established around a horizontal heater tube (Nickel Alloy-Inconel 600) that is immersed in the aqueous bulk liquid. Chemical reactions are promoted within the vapor layer due to large temperature gradients inherent to film boiling. Product gas flow rates and chemical composition are analyzed to assess the extent that the FIBOR can promote chemical change of the reactant liquid mixture. Catalytic reaction and thermal decomposition (pyrolysis) in the FIBOR are investigated by using a catalyst coated tube and a bare tube respectively. The heater tube surface temperature is the central operating parameter. Pure ethylene glycol is examined and compared to previously reported results to assess the role of the heater diameter. This work extends the FIBOR concept to aqueous mixtures of ethylene glycol to explore if the FIBOR is capable of promoting steam reforming chemistry. The results show that the FIBOR has the potential to support both catalytic and thermal decomposition of aqueous ethylene glycol mixtures. Diluting ethylene glycol with water decreases the reaction of ethylene glycol but it also reduces the effects of carbon deposition or "coking." Peak product yields for thermal decomposition of pure ethylene glycol and aqueous mixtures of 90% (vol) and 80% (vol) ethylene glycol reached 4.5, 1.8 and 0.8 LPM/min[MIDDLE DOT]m2 respectively at an operating temperature of 1475K. Results for platinum and nickel based coatings converting an 80% (vol) ethylene glycol aqueous mixture achieved product yields approximately 3 -4 times higher than the case for a bare tube, however platinum showed slightly better overall performance with respect to product yields and resistance to deactivation. Thermochemical and gas chromatography analysis revealed the FIBOR's capability to convert organic aqueous mixtures through steam reforming. An upward shift in the boiling curve for the catalyst coated tubes was determined to be due to the endothermic nature of the chemical mechanism. Conversion of aqueous mixtures with a bare tube produced synthesis gas (syngas) with a lower ratio of H2:CO (1:1) compared to catalytic conversion which resulted in a significant enrichment of syngas products with hydrogen (H2:CO=3). This difference is attributed to the FIBOR's ability to promote steam reforming of ethylene glycol.